In recent years, on a SONET/SDH (Synchronous Optical NETwork/Synchronous Digital Hierarchy) network, a monitor/control system for monitoring/controlling a plurality of transport apparatuses (NE; Network Element) constitutes a DCN (Data Communication Network) (e.g., see International Publication Pamphlet No. WO2002/045352). FIG. 9 is a diagram illustrating a configuration of a conventional DCN.
As illustrated in FIG. 9, NEs in the DCN are managed based on areas. The areas 10 to 30 include gateway apparatuses (GNE) 11, 21, and 31 for transmission among areas. In each area, NEs 12 to 14, 22 to 24, and 32 to 34 can be managed. With the structure illustrated in FIG. 9, monitoring control information (information for monitoring or controlling NEs) can be transmitted among all NEs within the DCN. Furthermore, because the NEs are divided and managed based on each of the areas, the NEs are managed in a less complex way.
Because the NEs are divided and managed on the basis of each of the areas as illustrated in FIG. 9, the NEs are managed in a less complex way. The problem is that there is a limit to the number of NEs that can be managed in each area, and when the number of NEs connected is above this limit, transmission among the connected NEs is lost and thus the NEs are no longer monitored.
In order to solve the above-mentioned problems, there is an attempt, when the number of NEs connected is above the limit within the DCN, to divide the DCN so that the number of NEs that can be managed is increased. To divide the DCN, each NE does not terminate, at its own NE, the monitoring control information that is received from the NEs belonging to the DCN to be divided but transmits the monitoring control information to other NEs that are to be divided.
FIG. 10 is a diagram illustrating a division of the DCN (omitting GNE in FIG. 10). In the example illustrated in FIG. 10, NEs 41 to 46 included in the area 40 are divided into a group of NEs 41 to 44 (DCN 40a) and a group of NEs 45 and 46 (DCN 40b).
In the DCN divided as illustrated in FIG. 10, the NE 44 terminates, upon receiving monitoring control information from the NEs 41 to 43, the monitoring control information. When the NE 44 receives the monitoring control information from the NEs 45 and 46, the NE 44 passes the received monitoring control information through it (i.e., the NE 44 passes the monitoring control information received from the NE 45 through it to the NE 46 and passes through the monitoring control information received from the NE 46 through it to the NE 45).
To provide a diversity of customer services, it is demanded that the NE described above be able to flexibly change a configuration of transport apparatuses in harmony with various types of services. There have been developed a centralized control configuration that performs termination/monitoring control with a single termination processing unit and a dispersed control configuration that performs termination/monitoring control with a plurality of termination processing units.
However, dividing the DCN under the centralized control configuration causes an increase in processing load on the NE (transport apparatus), and dividing the DCN under the dispersed control configuration, to lessen processing load, causes an increase in complexity of signal wires within the NEs.
There is a significant demand that the division of DCN be introduced with an advantage of the dispersed control configuration that can disperse processing load and without an increase in complexity of signal wires within the NEs.